Utilization of Tryptophan-like Fluorescence as a Proxy for <i>E. coli</i> Contamination in a Mixed-Land-Use Karst Basin
Karst aquifers are susceptible to contamination by pathogenic microorganisms, such as those found in human and animal waste, because the surface and subsurface drainage are well integrated through dissolution features. Fecal contamination of water is commonly assessed by the concentration of thermot...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-03-01
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| Series: | Hydrology |
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| Online Access: | https://www.mdpi.com/2306-5338/10/4/74 |
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| author | Ryan T. Dapkus Alan E. Fryar Benjamin W. Tobin Diana M. Byrne Shishir K. Sarker Leonie Bettel James F. Fox |
| author_facet | Ryan T. Dapkus Alan E. Fryar Benjamin W. Tobin Diana M. Byrne Shishir K. Sarker Leonie Bettel James F. Fox |
| author_sort | Ryan T. Dapkus |
| collection | DOAJ |
| description | Karst aquifers are susceptible to contamination by pathogenic microorganisms, such as those found in human and animal waste, because the surface and subsurface drainage are well integrated through dissolution features. Fecal contamination of water is commonly assessed by the concentration of thermotolerant coliform bacteria, especially <i>E. coli</i>. This method is time-consuming, taking ≥18 h between the start of incubation and subsequent enumeration, as well as the time required to collect and transport samples. We examined the utility of continuous monitoring of tryptophan-like fluorescence (TLF) as a real-time proxy for <i>E. coli</i> in a mixed-land-use karst basin in the Inner Bluegrass region of central Kentucky (USA). Two logging fluorometers were sequentially deployed at the outlet spring. During storm flow, TLF typically peaked after discharge, which suggests that TLF transport in the phreatic conduit is likely related to sediment transport. The ability of TLF and other parameters (48 h antecedent precipitation, turbidity, and air temperature) to predict <i>E. coli</i> concentrations was assessed using the Akaike information criterion (AIC) applied to linear regression models. Because both the models and baseline concentrations of TLF differed between fluorometers, TLF and instrument interaction were accounted for in the AIC. TLF was positively correlated with <i>E. coli</i> and, in conjunction with antecedent precipitation, was the best predictor of <i>E. coli</i>. However, a model that included air temperature and antecedent precipitation but not TLF predicted <i>E. coli</i> concentrations similarly well. Given the expense of the fluorometers and the performance of the alternate model, TLF may not be a cost-effective proxy for <i>E. coli</i> in this karst basin. |
| first_indexed | 2024-03-11T04:58:22Z |
| format | Article |
| id | doaj.art-bb6ff059fd9347a086dd1356145a5cbd |
| institution | Directory Open Access Journal |
| issn | 2306-5338 |
| language | English |
| last_indexed | 2024-03-11T04:58:22Z |
| publishDate | 2023-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Hydrology |
| spelling | doaj.art-bb6ff059fd9347a086dd1356145a5cbd2023-11-17T19:30:09ZengMDPI AGHydrology2306-53382023-03-011047410.3390/hydrology10040074Utilization of Tryptophan-like Fluorescence as a Proxy for <i>E. coli</i> Contamination in a Mixed-Land-Use Karst BasinRyan T. Dapkus0Alan E. Fryar1Benjamin W. Tobin2Diana M. Byrne3Shishir K. Sarker4Leonie Bettel5James F. Fox6Department of Earth and Environmental Sciences, University of Kentucky, Lexington, KY 40506, USADepartment of Earth and Environmental Sciences, University of Kentucky, Lexington, KY 40506, USAKentucky Geological Survey, University of Kentucky, Lexington, KY 40506, USADepartment of Civil Engineering, University of Kentucky, Lexington, KY 40506, USADepartment of Earth and Environmental Sciences, University of Kentucky, Lexington, KY 40506, USADepartment of Civil Engineering, University of Kentucky, Lexington, KY 40506, USADepartment of Civil Engineering, University of Kentucky, Lexington, KY 40506, USAKarst aquifers are susceptible to contamination by pathogenic microorganisms, such as those found in human and animal waste, because the surface and subsurface drainage are well integrated through dissolution features. Fecal contamination of water is commonly assessed by the concentration of thermotolerant coliform bacteria, especially <i>E. coli</i>. This method is time-consuming, taking ≥18 h between the start of incubation and subsequent enumeration, as well as the time required to collect and transport samples. We examined the utility of continuous monitoring of tryptophan-like fluorescence (TLF) as a real-time proxy for <i>E. coli</i> in a mixed-land-use karst basin in the Inner Bluegrass region of central Kentucky (USA). Two logging fluorometers were sequentially deployed at the outlet spring. During storm flow, TLF typically peaked after discharge, which suggests that TLF transport in the phreatic conduit is likely related to sediment transport. The ability of TLF and other parameters (48 h antecedent precipitation, turbidity, and air temperature) to predict <i>E. coli</i> concentrations was assessed using the Akaike information criterion (AIC) applied to linear regression models. Because both the models and baseline concentrations of TLF differed between fluorometers, TLF and instrument interaction were accounted for in the AIC. TLF was positively correlated with <i>E. coli</i> and, in conjunction with antecedent precipitation, was the best predictor of <i>E. coli</i>. However, a model that included air temperature and antecedent precipitation but not TLF predicted <i>E. coli</i> concentrations similarly well. Given the expense of the fluorometers and the performance of the alternate model, TLF may not be a cost-effective proxy for <i>E. coli</i> in this karst basin.https://www.mdpi.com/2306-5338/10/4/74karstspringbacteriatryptophanfluorometerKentucky |
| spellingShingle | Ryan T. Dapkus Alan E. Fryar Benjamin W. Tobin Diana M. Byrne Shishir K. Sarker Leonie Bettel James F. Fox Utilization of Tryptophan-like Fluorescence as a Proxy for <i>E. coli</i> Contamination in a Mixed-Land-Use Karst Basin Hydrology karst spring bacteria tryptophan fluorometer Kentucky |
| title | Utilization of Tryptophan-like Fluorescence as a Proxy for <i>E. coli</i> Contamination in a Mixed-Land-Use Karst Basin |
| title_full | Utilization of Tryptophan-like Fluorescence as a Proxy for <i>E. coli</i> Contamination in a Mixed-Land-Use Karst Basin |
| title_fullStr | Utilization of Tryptophan-like Fluorescence as a Proxy for <i>E. coli</i> Contamination in a Mixed-Land-Use Karst Basin |
| title_full_unstemmed | Utilization of Tryptophan-like Fluorescence as a Proxy for <i>E. coli</i> Contamination in a Mixed-Land-Use Karst Basin |
| title_short | Utilization of Tryptophan-like Fluorescence as a Proxy for <i>E. coli</i> Contamination in a Mixed-Land-Use Karst Basin |
| title_sort | utilization of tryptophan like fluorescence as a proxy for i e coli i contamination in a mixed land use karst basin |
| topic | karst spring bacteria tryptophan fluorometer Kentucky |
| url | https://www.mdpi.com/2306-5338/10/4/74 |
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